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Topic: Shuttle Q&A Part 5 (Read 1007985 times)

To keep everything at readable proportions, this is part 5 of the highly informative thread. Below are the links to previous parts. Please use the search function to see if your question has been answered before. Have Fun!

In a big emergency they might land there (edit -- probably only considered for low-inclination flights, which are now concluded), but the execute packages for 125 noted that Banjul was "politically not recommended."

In the sense of "the runway is big enough and is equipped with the proper navaids", yes.

In the sense of "would NASA ever land there", no. Groom Lake is not on the ELS list. There are other air force bases in that area of Nevada (e.g. Nellis) that are also suitable for the shuttle and aren't nearly as classified. There is no conceivable circumstance where the shuttle would be able to land at Groom Lake but not one of these other fields. Therefore it will never, ever happen.

I have some questions about some aspects of the Space Shuttle's ascent procedures:

1. When had the OMS assist burn during ascent (on Direct Insertion) been introduced for the first time?2. Which missions used the OMS assist burn during ascent? Is there a list available somewhere? 3. To me, it seems like all ISS missions used it, is that correct? What about other missions (e.g. Mir missions and others)? On the Ascent checklists that are available on the web, I noticed that the Hubble missions did not have an OMS assist burn, as well as STS-400.4. What are the reasons that determine, if an OMS assist is needed during ascent? Is it only the ET reentry footprint on certain inclinations? Does it also depend on the total weight of the orbiter (incl. payload)? Other factors?

5. When had the Roll to Heads Up been introduced for the first time?6. Which missions had performed the Roll to Heads Up? Is there a list available?7. I have read that the reason for the introduction of Roll to Heads Up was, to establish the comm link with a TDRS satellite during ascent, which in turn made a tracking station on the Bermudas obsolete. So, I assume that after a certain point in the history of the Shuttle program all missions performed the Roll to Heads Up. Is this correct?

« Last Edit: 06/14/2009 03:19 PM by Zero-G »

Logged

"I still don't understand who I am: the first human or the last dog in space." - Yuri Gagarin

I have some questions about some aspects of the Space Shuttle's ascent procedures:

1. When had the OMS assist burn during ascent (on Direct Insertion) been introduced for the first time?

STS-90, 1998.

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2. Which missions used the OMS assist burn during ascent? Is there a list available somewhere?

Don't know of a list. Most flights have used it.

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3. To me, it seems like all ISS missions used it, is that correct? What about other missions (e.g. Mir missions and others)? On the Ascent checklists that are available on the web, I noticed that the Hubble missions did not have an OMS assist burn, as well as STS-400.

There was only one Mir mission after STS-90 (STS-91). Don't know if it used OMS assist but it probably did. HST missions do not use OMS assist because they need all their OMS prop for in-mission usage. Roughly speaking, they burn half the tanks getting up to HST and the other half for deorbit.

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4. What are the reasons that determine, if an OMS assist is needed during ascent? Is it only the ET reentry footprint on certain inclinations? Does it also depend on the total weight of the orbiter (incl. payload)? Other factors?

Reentry footprint doesn't have anything to do with it. OMS assist is performed if 1) the OMS prop required for the mission itself does not require full tanks and 2) the mission could benefit from the additional payload capacity gained by filling the OMS tanks full and burning the difference as OMS assist (IIRC it's roughly 200 lb payload for 4000 lb OMS prop). CG location is a secondary consideration on the amount loaded.

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5. When had the Roll to Heads Up been introduced for the first time?

Don't remember for sure, think it was STS-86. (If it wasn't, it was another flight that year, 1997).

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6. Which missions had performed the Roll to Heads Up? Is there a list available?

No public list I'm aware of.

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7. I have read that the reason for the introduction of Roll to Heads Up was, to establish the comm link with a TDRS satellite during ascent, which in turn made a tracking station on the Bermudas obsolete. So, I assume that after a certain point in the history of the Shuttle program all missions performed the Roll to Heads Up. Is this correct?

Think so. RTHU does cost some performance so there were a handful of performance critical missions, after introduction of RTHU but before closure of Bermuda, that did not perform it. Off the top of my head I think STS-97 and 98 didn't but I'm not sure.

I have some questions about some aspects of the Space Shuttle's ascent procedures:

1. When had the OMS assist burn during ascent (on Direct Insertion) been introduced for the first time?2. Which missions used the OMS assist burn during ascent? Is there a list available somewhere? 3. To me, it seems like all ISS missions used it, is that correct? What about other missions (e.g. Mir missions and others)? On the Ascent checklists that are available on the web, I noticed that the Hubble missions did not have an OMS assist burn, as well as STS-400.4. What are the reasons that determine, if an OMS assist is needed during ascent? Is it only the ET reentry footprint on certain inclinations? Does it also depend on the total weight of the orbiter (incl. payload)? Other factors?

5. When had the Roll to Heads Up been introduced for the first time?6. Which missions had performed the Roll to Heads Up? Is there a list available?7. I have read that the reason for the introduction of Roll to Heads Up was, to establish the comm link with a TDRS satellite during ascent, which in turn made a tracking station on the Bermudas obsolete. So, I assume that after a certain point in the history of the Shuttle program all missions performed the Roll to Heads Up. Is this correct?

Roll to Heads up started with STS-87 and was standard after that. It was initiated by the program because of the expected closing of Bermuda.

OMS Assist capability was implemented with the OI-26 software, I will have to check which flight did it first. From a quick search it looks like it was STS-90 but I seem to remember being in the simulator with John Young (yes name dropping) the night before STS-92 because of cg concerns he had with the OMS assist and subsequent aborts - I thought that was the first flight but I will have to double check I just don't remember but wiki is saying STS-90. STS-90 might have tested the concept prior to an actual heavy station mission.

Mark Kirkman

P.S.

Yep, I checked my notes and it was indeed a test objective on STS-90 which was the neurolab flight and not a station mission.

ok i dont understand. by "range" im assuming NASA means the entire sky right? maybe a certain radius of it anyway? since the sky is all open and just "there" I dont get what this conflict is about? so what if numerous ships have a launch schedule close together, launch one, say at 10am, then launch another at 1030am---so what? why does the range only allow a certain vessel at a time to only launch at a certain period? the sky is the sky. Once something launches and clears, why cant another go right after it? even a day later, why is it still closed off?

ok i dont understand. by "range" im assuming NASA means the entire sky right? maybe a certain radius of it anyway? since the sky is all open and just "there" I dont get what this conflict is about? so what if numerous ships have a launch schedule close together, launch one, say at 10am, then launch another at 1030am---so what? why does the range only allow a certain vessel at a time to only launch at a certain period? the sky is the sky. Once something launches and clears, why cant another go right after it? even a day later, why is it still closed off?

The antennas need to be reconfigured for the LVs trajectory heading. They don't cover the entire sky at once - they're directional dishes, not simple radio aerials.

Mostly when they say "the range" they are referring to the dishes that allow telemetry from the rockets to be fed to the mission control centers. The dishes also track the rocket's path through the sky to make certain it doesn't go off course and threaten civilian populations. They also allow the flight control officer to destruct the rocket if it does go off course.

And yes, the shuttle (specifically the SRBs) has a flight termination system.

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Grant Imahara: Oxygen deficiency alarm? Is that something I should be worried about?NASA worker: Only if it goes off.

Sorry if I steped on Jorge's answers earlier but they weren't visible when I typed mine.

As for RTHU, after STS-87 I think ALL flights performed the roll because it was implemented based on the performance enhancement certifications. Flight Procedures Handbook states it is REQUIRED for low inclination flights for that reason alone. FPH also states that roll costs about 35 lbs in performance.

I have the STS-97 checklist Jorge referred to in my files so I can look that up to confirm.

OMS Assist capability was implemented with the OI-26 software, I will have to check which flight did it first. From a quick search it looks like it was STS-90 but I seem to remember being in the simulator with John Young (yes name dropping) the night before STS-92 because of cg concerns he had with the OMS assist and subsequent aborts - I thought that was the first flight but I will have to double check I just don't remember but wiki is saying STS-90. STS-90 might have tested the concept prior to an actual heavy station mission.

Mark Kirkman

P.S.

Yep, I checked my notes and it was indeed a test objective on STS-90 which was the neurolab flight and not a station mission.

Have there been any other tests after the first one on STS-90, or was this the only one?After the test(s), what was the first mission that used OMS Assist?Since then, which missions have used OMS assist (or which have not, apart from the HST missions)?Would a LON mission to the ISS also use OMS assist, or would this not be necessary, as there would be no payload on board?

« Last Edit: 06/15/2009 11:42 AM by Zero-G »

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"I still don't understand who I am: the first human or the last dog in space." - Yuri Gagarin

"OMS assist is performed if 1) the OMS prop required for the mission itself does not require full tanks and 2) the mission could benefit from the additional payload capacity gained by filling the OMS tanks full and burning the difference as OMS assist (IIRC it's roughly 200 lb payload for 4000 lb OMS prop). CG location is a secondary consideration on the amount"

I thought OMS assist was used if payload was -TOO heavy-, otherwise it seems to me that it would be a waste of money too -just burn off- the OMS prop like that?